Face aux enjeux énergétiques d’aujourd’hui et de demain, le développement des énergies renouvelables semble inéluctable. Cependant, la production électrique de sources renouvelables prometteuses comme le photovoltaïque ou l’éolien est intermittente et difficilement prévisible du fait de la dépendance de ces sources aux conditions météorologiques. Afin de s’affranchir du caractère discontinu de la production d’électricité et de l’inadéquation de la production avec la consommation, un moyen de stockage de l’énergie électrique est nécessaire. Dans ce contexte, la batterie hydrogène est une des solutions envisagées. Lors de périodes de surproduction d’énergie renouvelable, un électrolyseur produit de l’hydrogène par électrolyse de l’eau. Lorsque cela est nécessaire, une pile à combustible fournit de l’électricité à partir du gaz stocké. Couplé avec des sources d’énergie renouvelable, la batterie hydrogène produit de l’énergie électrique non carbonée, c’est-à-dire non émettrice de gaz à effet de serre. L’intérêt majeur de cette technologie est le découplage entre l’énergie et la puissance du système. Tant que la pile à combustible est alimentée en gaz, elle fournit de l’électricité, l’énergie dépend des réservoirs de gaz. La puissance, quant à elle, dépend des caractéristiques des composants électrochimiques et du dimensionnement des chaînes de conversions de puissance. Les chaînes de conversion de puissance relient les composants électrochimiques au réseau électrique. Dans le cas de la chaîne de conversion sans transformateur qui est ici envisagée, la présence d’un convertisseur DC-DC à haut rendement à fort ratio de conversion est rendue nécessaire de par la caractéristique basse tension fort courant des composants électrochimiques. Avec pour but principal l’optimisation du rendement, deux axes de recherche sont développés. Le premier axe développe un convertisseur multicellulaire innovant à haut rendement à fort ratio de conversion. Les résultats expérimentaux du convertisseur appelé « miroir » obtenus dans deux expérimentations ont démontré la supériorité de cette topologie en terme d’efficacité énergétique par rapport aux convertisseurs conventionnels. Le deuxième axe porte sur de nouveaux composants de puissance en nitrure de gallium (GaN) annoncés comme une rupture technologique. Un convertisseur buck multi-phases illustre les défis technologiques et scientifiques de cette technologie et montre le fort potentiel de ces composants. / Development of renewable energy seems inevitable to face the energy challenge of today and tomorrow. However, the power generation of promising renewable sources such as solar or wind power is intermittent and unpredictable due to the dependence of the these sources to the weather. In order to overcome the discontinuous nature of the electricity production and the mismatch between production and consumption, electrical energy storage is needed. In this context, hydrogen battery is one of the solutions. During periods of overproduction of renewable energy, an electrolyzer produces hydrogen gas by the electrolysis of water. When necessary, a fuel cell provides electricity from the stored gas. Coupled with renewable energy sources, the hydrogen battery produces carbon-free electricity, i.e. without any greenhouse gas emission. The major advantage of this technology is the decoupling between energy and power system. As long as the fuel cell is supplied with gas, it supplies electricity. Like so, the energy depends on the gas tanks and the system power depends on the characteristics of electrochemical components and the design of the power conversion chain. Power converters connect electrochemical components to the grid. In the case of the transformerless conversion system introduce here, a high efficiency high voltage gain DC-DC converter is required given the high-current low-voltage characteristic of electrochemical components. Since the main goal is to optimize the efficiency, two research approaches are developed. The first develops an innovating multicell converter with high efficiency at high voltage conversion ratio. The experimental results of the “mirror” converter obtained in two experiments have demonstrated the superiority of this topology in terms of energy efficiency compared to conventional converters. The second line of research focuses on new gallium nitride (GaN) transistors heralded as a disruptive technology. A multiphase buck converter illustrates the technological and scientific challenges of this technology and shows the potential of these transistors.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-03-13T15:20:14Z No. of bitstreams: 1 salatieldecastrolobato.pdf: 51678452 bytes, checksum: 022776c88833a1e47901180ebd1f826b (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-03-13T19:33:17Z (GMT) No. of bitstreams: 1 salatieldecastrolobato.pdf: 51678452 bytes, checksum: 022776c88833a1e47901180ebd1f826b (MD5) / Made available in DSpace on 2017-03-13T19:33:17Z (GMT). No. of bitstreams: 1 salatieldecastrolobato.pdf: 51678452 bytes, checksum: 022776c88833a1e47901180ebd1f826b (MD5) Previous issue date: 2016-11-07 / O objetivo geral desta dissertação é o aperfeiçoamento do projeto de uma nova fonte de corrente em desenvolvimento para o acelerador de partículas Sirius. A corrente da fonte é aplicada em magnetos de elevada indutância e são programadas para apresentar forma de onda com significativa componente senoidal em corrente contínua e em baixa frequência, de acordo com as características operacionais necessárias do Sirius. Para efeitos de estudo, a metodologia empregada consiste essencialmente em desacoplar a análise e o projeto do controle em um estágio regulador de tensão seguido de um estágio de síntese da corrente. Foram realizados ensaios em uma fonte em construção no Laboratório Nacional de Luz Síncroton e em um protótipo desenvolvido na UFJF. As principais contribuições descritas nesta dissertação são: i) atenuação da propagação de distúrbios de baixa frequência para a rede elétrica; ii) emprego de retificador de tensão controlado para regulação da tensão do barramento CC, melhoria do fator de potência e redução de componentes harmônicas. Os resultados experimentais evidenciam que as alterações de projeto propostas nesta dissertação apresentam grande potencial para melhorar o desempenho da fonte de corrente em termos da qualidade de energia elétrica e da sintetização de corrente senoidal no magneto do acelerador de partículas. / This work consists in the evaluation and improvement of a current source for a particle accelerator. The output current presents a DC sinusoidal waveform in low frequecy which flows through the windings of high inductance electromagnets. The methodology consists in separating the analysis and project of the control into two parts: a voltage regulator stage,followedbyacurrentsynthesisstage. Testswereperformedonacurrentsourceunder construction at the Brazilian Synchrotron Light Laboratory (LNLS) and on a prototype developed at UFJF. The work main contributions are: i) Attenuation of the low frequency disturbances on the electrical grid; ii) Use of a controlled rectifier to regulate the voltage of the DC bus, improvement in power factor and reduction of harmonic components. The experimental results show that the proposed changes have potential in improving the performace of the current source in terms of its electric power quality and synthesis of sinusoidal current in the particule accelerator.

This thesis dealing with description and of autonomous solar systems and algorithms for control of decision-making mechanism. Optimal set of these machanism has effeect in raise of efficiency in hole autonomous system. In practical purposes propose create one by using microprocesor ATMEGA8, which measure all electrical data in system and control all decisions of implemented algorithm.

All DC/DC converter products include power electronic circuits for power conversion.It is important to find an efficient way for power conversion to reduce power losses and reduce the need for cooling and achieve environmentally friendly solutions.The use of semiconductor switches of wide band gap type is a solution to the problem.Therefore, the investigation of the SiC MOSFET in DC/DC converters is of crucial importance for the reduction of power losses.The thesis investigates the SiC MOSFET in three different tests.The efficiency test, the temperature test and the double pulse test.In the efficiency, the MOSFET STC3080KR and NTH4L022N120M3S are compared with their respective simulation made on PLECS.While in the temperature test the STC3080KR is investigated at different frequencies.In Double Pulse Test the MOSFET STC3080KR with 4-pin (TO-247 4L) package is compared with the MOSFET SCT3080KLHRC11 with 3-pin package (TO-247 N).The efficiency test shows that the MOSFET SCT3080KR in the practical test gives an efficiency in the range of 96,5-96,1% at 110kHz, 96-95,4% at 150kHz and 95,8-94,2% at 180kHz.While, the NTH4L022N120M3S gives an efficiency in the range of 98,1-97,1% at 110kHz, 96,3-96,2% at 150kHz and 96,1-95,5% at 180kHz.The efficiency given by the simulation is higher than the actual efficiency for both MOSFETs.However, the shape of the curves in the practical part matches the simulated one.The efficiency is not the same since the simulation do not consider all the losses present in the practical part.The temperature test shows that the temperature for the high side and low side increases when the frequency and the load current increases.However, some results show that when the load current increases at some point the low-side MOSFET will reach the temperature of the high-sided MOSFET and at the end it will exceed its value. This is due to the increment of the conduction losses since the low side MOSFET is basically the body diode incorporated in the MOSFET.Finally, the Double Pulse Test shows that the TO-247 N (3-pin) package switches with less source inductance compared to the TO-247 4L (4-pin) package.Therefore, the MOSFET SCT3080KLHRC11 (TO-247 N package) needs more time during the switching and which means that the switching power losses will be higher in comparison to the SCT3080KR as shown in Table 5.2 and Table 5.1. / Alla DC/DC-omvandlarprodukter inkluderar kraftelektroniska kretsar för effektomvandling. Detta gör att det är viktigt att hitta ett effektivt sätt för effektomvandlingen för att minska effektförlusterna och minska behovet av kylning och uppnå miljövänliga lösningar.Användningen av halvledaromkopplare med ett stort bandgap är en lösning på problemet.Därför är undersökningen av SiC MOSFET i DC/DC-omvandlare av avgörande betydelse för att minska effektförlusterna. Detta examensarbete undersöker SiC MOSFET i tre olika tester vilket är; Effektivitetstestet, temperaturen testet och double pulse testet.I effektivitets testet jämförs MOSFET STC3080KR och NTH4L022N120M3S med deras respektive simulering gjorda på PLECS.Medan i temperaturtestet undersöks STC3080KR vid olika frekvenser.I double pulse testet jämförs MOSFET STC3080KR med ett 4-stifts (TO-247 4L)-paket med MOSFET SCT3080KLHRC11 med ett 3-stiftspaket (TO-247 N).Effektivitetstestet visar att MOSFET SCT3080KR i det praktiska testet ger en verkningsgrad i intervallen 96,5-96,1% vid 110kHz, 96-95,4% vid 150kHz och 95,8-94,2% och vid 180kHz.Medan NTH4L022N120M3S visar en effektivitet i intervallet av 98,1-97,1% vid 110kHz, 96,3-96,2% vid 150kHz och 96,1-95,5% vid 180kHz.Verkningsgraden som ges av simuleringen är högre än den praktiska för båda MOSFET:erna.Formen på kurvorna i den praktiska delen matchar den simulerade.Verkningsgraden är inte densamma eftersom simuleringen inte tar hänsyn till alla förluster som finns i den praktiska delen.Temperaturtestet visar att temperaturen för den höga sidan och lågsidan ökar när frekvensen och belastningsströmmen ökar.Vissa resultat visar att när belastningsströmmen ökar lågsidans MOSFET når temperaturen hos den högsidiga MOSFET:en och i slutet kommer den att överstiga dess värde.Detta beror på ökningen av ledningsförlusterna eftersom MOSFET på lågsidan i grunden är kroppsdioden som ingår i MOSFET.Slutligen, visar double pulse testet att TO-247 N (3-stifts)-paketet växlar med mindre källinduktans jämfört med till TO-247 4L (4-stifts)-paketet.Därför behöver MOSFET SCT3080KLHRC11 (TO-247 N-paket) mer tid under växlingen och därför blir växlingseffektförlusterna högre jämfört med SCT3080KR, detta visas i Tabell 5.2 och Tabell 5.1.

<p dir="ltr">The short lifespan of capacitors in power electronics converters is a significant challenge. These capacitors, often electrolytic, are vital for voltage smoothing and frequency filtering. However, their susceptibility to heat, ripple current, and aging can lead to premature faults. This can cause issues like output voltage instability and short circuits, ultimately resulting in catastrophic failure and system shutdown. Capacitors are responsible for 30% of power electronics failures.</p><p dir="ltr">To tackle this challenge, scientists, researchers, and engineers are exploring various approaches detailed in technical literature. These include exploring alternative capacitor technologies, implementing active and passive cooling solutions, and developing advanced monitoring techniques to predict and prevent failures. However, these solutions often come with drawbacks such as increased complexity, reduced efficiency, or higher upfront costs. Additionally, research in material science is ongoing to develop corrosion-resistant capacitors, but such devices are not readily available.</p><p dir="ltr">This dissertation presents a capacitorless solution for dc-dc and dc-ac converters. The proposed solution involves harnessing parasitic elements and integrating them as intrinsic components in power converter technology. This approach holds the promise of enhancing power electronics reliability ratings, thereby facilitating breakthroughs in electric vehicles, compact power processing units, and renewable energy systems. The central scientific premise of this proposal is that the capacitance requirement in a power converter can be met by deliberately augmenting parasitic components.</p><p dir="ltr">Our research hypothesis that incorporating high dielectric material-based thin-films, fabricated using nanotechnology, into planar magnetics will enable the development of a family of capacitorless electronic converters that do not rely on discrete capacitors. This innovative approach represents a departure from the traditional power converter schemes employed in industry.</p><p dir="ltr">The first family of converters introduces a novel capacitorless solid-state power filter (SSPF) for single-phase dc-ac converters. The proposed configuration, comprising a planar transformer and an H-bridge converter operating at high frequency, generates sinusoidal ac voltage without relying on capacitors. Another innovative dc-ac inverter design is the twelve step six-level inverter, which does not incorporate capacitors in its structure.</p><p dir="ltr">The second family of capacitorless topologies consists of non-isolated dc-dc converters, namely the buck converter and the buck-boost converter. These converters utilize alternative materials with high dielectric constants, such as calcium copper titanate (CCTO), to intentionally enhance specific parasitic components, notably inter capacitance. This innovative approach reduces reliance on external discrete capacitors and facilitates the development of highly reliable converters.</p><p dir="ltr">The study also includes detailed discussions on the necessary design specifications for these parasitic capacitors. Furthermore, comprehensive finite element analysis solutions and detailed circuit models are provided. A design example is presented to demonstrate the practical application of the proposed concept in electric vehicle (EV) low voltage side dc-dc power converters used to supply EVs low voltage loads.</p>